Method of treatment and heterocyclic compounds used therein

A method of treating pain in a mammal so afflicted which comprises administering to said mammal an effective amount of a compound having the formula ##STR12## (R).sub.n represents optional substitution on the benzene ring in one or more of the vacant ring positions by one or more substituents the same or different selected from lower alkyl, lower alkoxy, halogen, hydroxy, nitro, carboxy, lower alkylthio, SH, NH.sub.2, or mono- or diloweralkylamino or (R).sub.n represents disubstitution by an alkylenedioxy radical;

• R.sup.1 represents hydrogen, lower alkyl, aryl, or aryl lower alkyl, the aryl and aryl lower alkyl groups being optionally substituted by one or more substituents the same or different selected form hydroxy, halogen, lower alkyl, lower alkoxy, NO.sub.2, CN, carboxy, lower alkylthio, SH, NH.sub.2 and mono- or di-loweralkylamino or by alkylenedioxy;
• R.sup.2 represents hydrogen or lower alkyl;
• and A represents phenyl, furanyl, pyrrolyl, thienyl, pyranyl, pyridyl, or thiazolyl optionally substituted as for R.sup.1 when phenyl, furanyl, pyrrolyl, thienyl, pyranyl, pyridyl, or thiazolyl or a group of the formula ##STR13## wherein the dotted lines represent optional bonds, X represents NH, oxygen, or sulphur and R.sup.3 represents hydrogen or lower alkyl;
• or a pharmaceutically acceptable salt thereof.